If you install Adobe Acrobat Reader on recent versions of 64-bit Ubuntu you may see errors like the following:
/opt/Adobe/Reader9/Reader/intellinux/bin/acroread: error while loading shared libraries: libgdk_pixbuf_xlib-2.0.so.0: cannot open shared object file: No such file or directory
This is caused by missing 32-bit libraries. You can install the ones you need as follows:
sudo apt-get install libgtk2.0-0:i386 libgdk-pixbuf2.0-0:i386
Joe Halliwell's Blog 